Any ATA-6 drive should be OK. I think the Toshiba that I have is an ATA-6 drive. Just make sure you get a 2.5" drive, 9.5 mm height MAX.
While you're inside the iBook, there are a couple of things you need to be really careful with.
1. Use the right sized screwdrivers. You don't want to strip the wrong ones.
2. Be extremely careful when disconnecting the trackpad ribbon. The connector that the ribbon sits in is connected to the motherboard and can be very fragile. You don't want to snap that connector off like I did. Otherwise you'll be using a mouse all the time.
3. Get a good take-apart guide (try pbfixit.com) and keep track of all your screws.
4. Be patient when trying to take the bottom casing off. You don't want to crack that case.
5. Lastly, when putting everything back together, don't forget the magnet that sits on the right side of the case, just below the optical drive.
Good Luck. With a little patience, you'll be able to swap the drive out.
ft
EDIT - check out xlr8yourmac.com and the Drive Compatibility chart. You'll see other people who have swapped out their hard drives and their opinions and tips.